People with chronic health conditions are being asked to do more and more to maintain their health. This chronic workload can negatively impact well being, reduce adherence to treatment, and ultimately jeopardize long-term clinical outcome. Not only does this harm the patient, but it may lead to higher healthcare costs as poorer outcomes require more aggressive treatment. One way to mitigate this problem is to reorient clinical care by finding a balance between care that is necessary and care that is minimally disruptive to the patient. An initial step toward achieving this is to establish the weigt of treatment burden for the patient managing one or more chronic health conditions. We define the burden of treatment (BoT) as the negative impact of the workload of healthcare on patient functioning and well-being. While some attempts have been made to measure BoT within specific disease and treatment settings, its scope in primary care and in patients with multiple chronic conditions is less understood. Currently, there is no general measure of BoT flexible enough for use across a wide spectrum of diseases and treatments. Our goal in this project is to create and validate such a measure. We will accomplish this through the completion of the following aims: (1) construction of a conceptual framework of BoT using patient interviews and focus groups; (2) generation, review, and pre-testing of a pilot measure of BoT using measurement experts, clinical experts, and patients; and (3) pilot testing of a new BoT measure in 200 patients with complex medical conditions. Having a valid, patient-reported measure of BoT available for use in primary care would be valuable. At present, there is only limited understanding of the care burden shouldered by patients dealing with multiple comorbidities and/or complex medical conditions. A general BoT measure would allow for more rigorous scrutiny of how such patients manage (or fail to manage) these challenging medical situations. A BoT measure could be used as an outcome in a wide variety of clinical trials or in studies of comparative effectiveness, helping identify treatments that are least intrusive on a patient's life Such a measure could also be employed clinically as a screen for patients who might be at risk for treatment non-adherence. Following successful completion of this project, we will use the measure in prospective studies to further investigate its psychometric properties (e.g., responsiveness to change) and better understand how its scores can be interpreted. This will include evaluations of supportive clinical services like pharmacy-led medication management, studies comparing the overall self-care burden of competing treatment regimens, and studies of shared medical decisions.